Robert P. Stiller, founder and chairman of Green Mountain Coffee Roasters Inc. (GMCR), sold $66.3 million of his stock before it plunged the most in four months on news that Starbucks Corp. (SBUX) had developed a rival to its K-Cup brewer.

Stiller's combined sales on Feb. 15 and 24 were his largest in a single month since at least 2003, when the stock traded below $2, data compiled by Bloomberg show. He would have received $13.7 million less had he sold after March 9, when the shares fell 16 percent on Starbucks' introduction of a machine for home-brewing single cups of espresso and coffee, a challenge to Green Mountain's Keurig system.

Green Mountain Coffee K-Cups at the company's visitor center and cafe in Waterbury, Vermont on Feb. 18, 2011. Photographer: Herb Swanson/Bloomberg

"We recently learned of Starbucks' planned initiative in the espresso-based single-cup category," Green Mountain said in a March 9 regulatory filing, a day after the machine was announced. "However, we were not made aware of any additional capabilities." Spokesmen for Green Mountain wouldn't specify when it learned of the plan.

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Article by Max Abelson and Leslie Patton
Bloomberg News PR